Title: Effects of diagonal strains and H-bond geometry in antiferroelectric squaric acid crystals
Author(s):

A.P. Moina (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine)

The proton ordering model of the phase transition and physical properties of antiferroelectric crystals of squaric acid is modified by taking into account the influence of diagonal lattice strains and of the local geometry of hydrogen bonds, namely of the distance δ between the H-sites on a bond. Thermal expansion, the spontaneous strain ε₁–ε₃, and specific heat of squaric acid are well described by the proposed model. However, a consistent description of hydrostatic pressure influence on the transition temperature is possible only with further modifications of the model.

Key words: antiferroelectricity, hydrogen bond, phase transition, thermal expansion, hydrostatic pressure

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